Telephone-transmission system



Patented Nov. 14, 1922.

hven/or: W/7/x'dm f7 Bendernage/ W. H. BENDERNAGEL. TELEPHONE TRANSMISSION SYSTEM.

- APPLICATION FILE D DEC-9, 1919- A L .W s .P We w m k T L. e A Z Z A F v WILLIAM H. BENDERN'AGEL, 0F QUEENS, NEW'YORK, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION or NEW Yoax.

TELEPHONE-TRANSMISSION SYSTEM.

To all whom it may concern Be it known that I, WILLIAM H. BEN- DERNAGEL, a citizen of the United States, residing at Queens, in the county of Queens,

53 State of New York, have invented certain new and useful Improvements invTelephone- -Transmission'systems, of which the following is a full, clear, concise, and exact description.

This invention relates to a telephone transmission system. The object of the invention is to provide an ,am-plifyimg repeater in a link or cord circuit of such a system.

One of the features of the Invention is to provide two balancing lines for an amplifier at the answering end of the cord or link circuit, so as to balance the calling subscribers line alone, or the calling line and the operators tele hone line or set when the two are connecte to the cord or ringing circuit. In theparticular embodiment of the invention described and illustrated in this application, this is accomplished by 2e providing a balancing net-work consisting of two sections so arranged that one section may be used to balance the calling line, and the two sections will be automatically thrown in parallel to balance the calling line and the operators set when the operators listening key is pressed.

Another feature of the invention is to connect the repeater in the cord or link circuit, and to rovide battery for talking purposes to subscribers lines which may be connected to either end of the cord circuit. In the embodiment shown. this is accomplished by splitting the repeating coil of a cord circuit and connecting a battery for feeding the lines that are connected to each section, while the amplifier is connectedvin between the sections of the split repeating coil.

Another feature of the invention is to provide a single relay which is both marginal and differential in a subscribers cord circuit and so connecting its windings that it may only be energized when both ends of the cord are plugged in line jacks to 50 render the amplifier active, and which may be de-energized by throwing the operators ringing key. By rendering the amplifier inactive when the ringing keys are thrown, no singing of the amplifier will take place at due to unbalance between the various networks caused by opening the connected lines whlle ringing. Plugging in of one end of the cord is without effect on said relay whereby incoming calls which are merely inquiries and do not involve the establishment of a connection to'another line or trunk do not place the amplifier in opera- 1on. I

The invention will be understood from the description in connection with the'accompanying drawing, which shows two subscribers sets and a cord circuit which is provided with two one-way amplifiers,-

and differential relay.

In the drawing, reference character A refers to a subscribers line which is provided with the usual telephone set, line relay, line lam etc. When the subscriber at A raises hlS telephone hook, a circuit is closed through relay 1, thus closing its contact and lighting the line lampL throughan obvious circult.

Upon noticing the signal at L, the operator inserts her plug P into the jack J of the calling subscribers line, thus closing a circuit through the cut-off relay 2. thereby deenergizing the relay 1 and extinguishing the lamp L. The insertion of the plug P into the jack J also closes a circuit from battery through the upper half of the lefthand winding of transformer T, tip contacts of plug P and jack J, telephone set of subscriber A; ring contacts of jack J and plug P, relay 3, lower half of the left-hand winding of transformer T back to battery. This energizes relay 3, thereby closing its contact which permits current to flow through a circuit which may be traced from ground through relay 2, sleeve contacts of jack J and plug P, contact of relay 3, wire 4, and coil a of relay 4, battery to ground.

Reference character 4: refers to arelay which is provided with three coils, a, b and 0. The coils a and b are so designed that neither when energized alone is suficient to operate the armature and contact. The coil 0 is wound. so as to oppose the coils a or b and is such that current through the coil 0 will neutralize the ener izing current through the coils a and b. T erefore when the plug P is inserted into jack J- the relay 4 will notenergize and the operator can, by throwing her listening ke In, answer any inquiry of the calling su scriber without afiecti 3 gthe am lifiers. When the operator desire to signa the called set-ts the plug P into the 'ack and throws her ringing'lkfigy K or s e may throw the ringing key before insertin the plug. In'either case the operation of ey K cuts 'ofi batter current from the subsgriber B and 'simu taneously establishes a circuit from groundthrough battery, coil 0, wire 4., to ground, thereby preventing the operation of relay t and the closing of the circuit through thefilaments of the amplifier thus rendering the amplifiers inoperative; en the plug P is inserted into the 'ack J, a circuit 1s established from groun through relay 2, sleeve contacts of jack J and plug 1?, lamp L wire 4, coil .6, batter to ground, thus lihting the lamp L hen the subscriber raises his telephone hook, as soon as the ringing key is returjned to normal position a circuit is established from battery through the upper half of the righthand winding of transformer T, tip contacts of plug P and jack J, set of subscriber B, rin contacts of jack J and plug P, relay 3, .ower half of the right-hand winding of transformer T to battery. This energizes relay 3, thereupon short-circuiting the lamp L,, and extinguishing the same. The operator observin the retiring of the signal L, allows the ringing ke to remain in normal position. As long as ey K was in the ringing (position, winding 0 prevented windings a an I; from operating the arm-ature of relay 4. When the subscriber B raises his receiverand key K is in normal position so that 3 operates and L, becomes short-circuited, the current through I) together with that from a is suflicient to operate the armature of relay 4. Theoper-ation of relay 4. establishes a circuit for the filaments of the repeater R and R, from battery, armature and contact of relay 4, conductor 5, filaments of R and R in series to ground.

The answering end of the cord or link circuit is rovided with a balancing net-work N whic consists of two'sections, n and 01,, so arranged that the section 11. is in series with the right-hand winding of transformer T and the primary of transformer t, thus operatin' as a balancer for the subscribers set A w en the plug P is in the jack J. When the operator presses her ke k, her telephone set is connected inpara lel with the subscriber A and contact is made at" 10,, thus connecting the section n, of net-work N in parallel with the section n, thereby providmg'a balancing net-work for both the suibscriber and the operators telephone se When both plugs are in their sacks and both telephone hooks are raise talking current is supplied to both connected subscribers from the batteries at transformers garty, she ininsane? T and T as'shown and the repeater is op erative. With these connections, current from subscriber A passes through the Jack J and lug P, relay 3, left-hand win ing of trans ormer T and battery. At the transformer" T, it s transformed to the right-hand winding w ere it passes through the circuit including the primar of transformer t and section 1:. of .net-Wor N. At t the current is transformed to the secondary where it passes to the input side of ampllfier R, and is amplified and passes to the out ut side of this amplifier to the circuit WhlCh includes the primary of transformer 23, the net-work N and the left-hand winding of transformer T, where it is tr-. formed to the right-hand winding of transformer T and thence passes through lug P and jack J to the subscriber B. alking current from the subscriber B passes through the connections in a similar way, except that itpasses through and is amplified by the amplifier R instead of the amplifier R. When the subscribers at A and B hang up their receivers, the circuits are broken through relays 3 and 3, thus. permitting their contacts to open thereby removing the short-circuits from lamps L and T1,, which light to 've the operator'the disconnect signals. he operatorthen withdraws plugs P and P. from the jacks J and J, which deenergizes the relay 4 and. opens its contact, thus rendering the amplifier inoperative and restoring the apparatus to normal condition.

What is claimed is: 1. In a telephone exchange system, a plurality of subscribers lines terminating at a central station, means for connecting said 105 lines, said means comprising. a repeater having a balancing network for one of said lines, a circuit, means for connecting said circuit to said means for connecting said lines, means whereby said balancing network can be so modified as to make it capable of balancing both said one line and said circuit, and means for rendering said last mentioned means effective upon the connection of said circuit to said means for connecting saidlines. g

2. In a telephone exchange system, a plurality of subscribers line circuits terminating at a central station, a link circuit, a repeater in said link circuit, an operators telephone set, a balancing network for a subscribers line connected to said link circuit, andmeans for changing the characteris tics of said network when said operators set is connected to said link circuit.

3. In a telephone exchange system, a plurality of subscribers line circuits terminatingat a central-station, a link circuit, a repeater in said link circuit, an operators telephone set, a balancing. i1etwork comprising rec ing two branches in parallel, one of said branches being connected to said link circuit and means for connecting said branches- "in parallel when said operators set is connected to said link circuit.

5. In a telephone exchange system, a plurality of subscribers line circuits terminating at a central station, a cordcircuit, a repeater in said cord circuit, and a source of current in said cord circuit on either side of saidrepeater for feeding connected subscribers lines.

6. In a telephone exchange system, a plurality of subscribers line circuits terminating at a central station, a link circuit, said link circuit comprising a repeating path in each direction between said lines, each of said paths including a single amplifying stage, and sources of electromotive force in said link circuit at each end thereof for feeding said subscribers lines,

7 In a telephone exchange system, a plurality of subscribers line circuits terminating at a central station, a link circuit, a

repeater in said link circuit, a transformer.

for connecting said repeater to one of said line circuits, a transformer for connecting said repeater to another of said line circuits, each of said transformers comprising only two inductively related windings, each of said windings having all of its turns wound cumulatively, and one of said windings on each transformer being provided with battery for feeding connected lines.

8. In a telephone exchange system, a plurality of subscribers lines, a link circuit, means for connecting said lines to said link circuit, means in said link circuit for signal-' in; the connected lines, and a repeater in said link clrcuit comprising an'ampllfying element rendered incapable of conducting current b the line connecting means and line signa ing means.

9. In a telephone exchange system a calling and a called line terminating at a central station, a link circuit for connecting said lines, a repeater comprising an amplifying element in said link circuit, means in said link circuit for signaling the connected lines, and means controlled by said signaling means for rendering said amplifying element capable of conducting current.

10. In a telephone exchange system, a plurality of subscribers line circuits terminating at a central station, a link circuit','comprising means for connecting said line circuits to said link circuit, a repeater in said link circuit, means in said linkcircuit for signaling the connected line circuits and a repeater controlling switch controlled by said connecting means and said signaling means.

11. In a telephone exchange system, a calling and a called line terminating at a central station, a link circuit, a repeater in said link circuit, and a combined marginal and differential relay for placing said repeaterunder the control of the connection of said link circuit with both of said lines and the disconnection of either of said lines.

12. In a telephone exchange system, a plurality of-subscribers line circuits terminating at a central station, a link circuit, a repeater in said link circuit, a balancing net-work for a subscribers line connected to the answering end of said link circuit, and a battery at each end of said link circuit for feeding connected subscribers lines.

13. In a telephone exchange system, a plurality of subscribers line circuits terminating at a central station, a link circuit, a repeater in said link circuit, a repeating transformer in said link circuit for connecting said repeater to one of said line circuits, said repeating transformer. having two inductivelyrelated windings, a source of direct current in circuit with only one ofsaid windings for feeding said one of said line my name this 5th day of December A. D.,

, WILLIAM H; BENDERNAGEL. 

